Making soft tissue and toweling products which promote comfortable cleaning without performance impairing sacrifices has long been the goal of the engineers and scientists who are devoted to research into improving tissue paper. There have been numerous attempts to reduce the abrasive effect, i.e., improve the softness of tissue products. One area which has received a considerable amount of attention is the addition of chemical softening agents (also referred to herein as “chemical softeners”) to tissue and toweling products.
The field of work in the prior art pertaining to chemical softeners has taken two paths. The first path is characterized by the addition of softeners to the tissue paper web during its formation either by adding an attractive ingredient to the vats of pulp which will ultimately be formed into a tissue paper web, to the pulp slurry as it approaches a paper making machine, or to the wet web as it resides on a Fourdrinier cloth or dryer cloth on a paper making machine. See U.S. Pat. No. 5,264,082, issued to Phan and Trokhan on Nov. 23, 1993, and U.S. Pat. No. 5,059,282, issued to Ampulski, et. al. on Oct. 22, 1991.
The second path is categorized by the addition of chemical softeners to tissue paper web after the web is dried or overdried. Applicable processes can be incorporated into the paper making operation as, for example, by spraying onto the dry web before it is wound into a roll of paper. Exemplary art from this field includes U.S. Pat. No. 5,215,626, issued to Ampulski, et. al. on Jun. 1, 1993; U.S. Pat. No. 5,246,545, issued to Ampulski, et. al. on Sep. 21, 1993; U.S. Pat. No. 5,525,345, issued to Warner, et. al. on Jun. 11, 1996, U.S. Pat. No. 6,162,329, issued to Vinson on Dec. 19, 2000, U.S. Pat. No. 6,179,691, issued to Ficke et al. on Jan. 30, 2001; U.S. Pat. No. 6,261,580, issued to Trokhan et al. on Jul. 17, 2001; U.S. Pat. No. 6,420,013, issued to Vinson et al. on Jul. 16, 2002, PCT Applications WO 00/22231 and 00/22233, filed in the name of Vinson et al., published on Apr. 20, 2000; and PCT Application WO 02/48458, filed in the name of Vinson et al., published on Jun. 20, 2002.
Those skilled in the art will recognize that both technology paths, more particularly the second path, are advanced by inventions of chemical softening mixtures having liposomal microstructures present at high concentration in a vehicle. The most recent of the development work in this area has focused on the improvement of the rheological properties of the chemical softening compositions. U.S. Pat. No. 6,162,329 teaches the use of high concentration compositions of softening agents which maintain a viscosity at a level where they can be easily applied to the web. Specifically, U.S. Pat. No. 6,162,329 teaches the addition of electrolytes to the composition. WO 00/22231 and 22233 further improve the rheology of the high concentration compositions by utilizing a bilayer disrupter to create a micellular structure which allows for more efficient application of the chemical softener to the paper web.
Unfortunately, the existing technology, while improving the rheology of liposomal softening compositions; does not, for example, reduce the viscosity of all quaternary esters to a level where they can effectively be used in the application processes of the paper making operation. For example, high concentration compositions of quaternized soft tallow-di-esterfied with methyldiethanolamine—form low viscosity compositions, however, high concentration compositions of quaternized soft tallow-di-esterified with triethanolamine is still a thick composition, which, for example, renders it incapable of being applied to paper webs at concentrations necessary to deliver high quality softening benefits.
Accordingly, it is desirable to find a way to further improve the rheology of liposomal softening compositions comprising quaternary amine compounds, to be able to use a wider variety of them in paper products. Such improved products, compositions, and processes are provided by the present invention as is shown in the following disclosure.